The invention generally relates to optical devices and their fabrication, and more particularly to an apparatus and method for precisely controlling the angular relationship between optical elements and a substrate plane within an optical device.
Optical filters are well known for use with optical devices, such as, for example, hybrid optical components. Conventional assembly methodologies for constructing optical devices, such as hybrid optical components, are generally designed such that optical elements are mounted in a single structural plane. Specifically, optic:al elements such as mirrors, filters, polarizers, beam splitters, lenses and other reflective or transmissive optical elements within the optical device are positioned and bonded in a single plane on a substrate surface. It is important to properly align the optical filters and other optical elements along the structural plane so that optical signal is not lost through improper transmission from one optical element to another.
Conventionally, optical elements utilized in optical devices have been epoxied or otherwise affixed to a substrate surface. Referring to FIGS. 1-3, an optical device 10 is shown having a carrier substrate 12. The optical device 10 has an optical input point 14 and an optical output point 40 positioned in the same structural plane. Further mounted on the carrier substrate 12 are a first optical element 18, a second optical element 28, and a third optical element 34, all mounted in the same structural plane. The optical elements 18, 28, 34 may be any reflective or transmissive optical elements, such as lenses, mirrors, polarizers, beam splitters, filters, or other like optical elements.
The first optical element 18 has a first surface 20 (FIG. 2), a second surface 22, and a reflecting surface 24. By design, optical signals from the input point 14 are to travel along a first signal pathway 16 and be reflected off of the reflecting surface 24 toward the second optical element 28. The reflected optical signals travel along a second signal pathway 26 and reflect off of a reflecting surface 30 of the second optical element 28. The twice reflected optical signals then travel along a third signal pathway 32 and are reflected off of a reflecting surface 36 of the third optical element 34 into a fourth signal pathway 38 leading to the output point 40.
In practice, as noted above, the optical elements 18, 28, 34 generally are affixed to the carrier substrate 12 through an epoxy 42. Specifically, as shown in FIG. 2, the epoxy 42 is deposited on a first surface 13 of the carrier substrate 12 and the optical elements 18, 28, 34 are each lowered into contact with the epoxy 42. Often, however, in lowering an optical element to be bonded to the carrier substrate 12, the optical element does not bond with the carrier substrate 12 such that the first surface 20 is parallel to the first surface 13. As illustrated in FIG. 3, the first optical element 18 has been lowered onto the epoxy 42, but remains at an angle to the first surface 13 of the carrier substrate 12. Improper alignment of the optical elements 18, 28, 34 leads to the transmission of optical signals out of the structural plane, thereby preventing the optical signals from reaching the output point 40.
The invention provides a mounting structure for mounting an optical element. The mounting structure includes a substrate having a first surface, a plurality of protrusions extending by a substantially equal amount from the substrate first surface, and one or more walls extending from the substrate first surface and surrounding the protrusions and defining a well.
The invention further provides an optical device which includes a substrate having a first surface, at least one mounting structure, and at least one optical element mounted on protrusions of the at least one mounting structure.
The invention further provides a method of mounting one or more optical elements onto an optical device having one or more mounting structures which include a plurality of protrusions surrounded by one or more walls defining a space. The method includes the steps of adding an epoxy material to the space, lowering the optical element into contact with the epoxy material, contacting the optical element to the protrusions, and curing the epoxy material.
The invention further provides a method of planarly aligning two or more optical elements mounted onto an optical device having two or more mounting structures which include a plurality of protrusions surrounded by one or more walls defining a space. The method includes the steps of adding an epoxy material to the space of each mounting structure, lowering each optical element into contact with the epoxy material in a respective space, contacting each optical element to the protrusions of a respective mounting structure, aligning each optical element to the other optical elements, and curing the epoxy material.
The foregoing and other advantages and features of the invention will be more readily understood from the following detailed description of the invention, which is provided in connection with the accompanying drawings.